Byzantine-Sassanian War (602-628 CE): The Last Great War of Antiquity

After many years of conflict, the Sassanians and Byzantines fought one last great war that nearly destroyed both empires.

Jun 3, 2023By Robert C. L. Holmes, MA Ancient & Medieval History, BA Archaeology

byzantine sassanian war


Ever since the rise of the Sassanian dynasty in the 3rd Century CE, the Persians had fought against their Roman or Byzantine neighbors. Though devastating, these wars were usually limited in scope. The Sassanians could defeat the Byzantines, but rarely could they match their resources. Over time, the balance of power shifted so that the two empires became more equal. When the conflict reignited in the early 7th Century CE, the Sassanians nearly succeeded in destroying the Byzantine Empire. It was only with the rise of the great soldier-emperor Heraclius (c.575-641 CE) and the use of clever diplomacy that the Byzantines were able to emerge victorious. Yet, the war that would come to be known as the “Last Great War of Antiquity” left both empires exhausted and unable to defend themselves from the rising power of the Islamic Rashidun Caliphate.


Before the Byzantine-Sassanian War

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Tremissis of Emperor Maurice (left), Byzantine 582-601 CE; with Solidus of Emperor Phocas (right), Byzantine 602-610 CE, From The Metropolitan Museum of Art


The previous conflict between the two great empires, the Byzantine-Sassanian War of 572-591 CE, ended with a promise of peace. Maurice (539-602 CE), the Byzantine emperor, helped an exiled prince Sassanian prince, Khosrow II (c.570-628 CE), ascend the throne. This resulted in cordial relations between the empires, with the Byzantines being able to halt annual tribute payments to the Sassanians. Both empires had been weakened by the conflict, and Khosrow needed to consolidate his rule. However, Maurice’s attempts to rebuild the imperial treasury and deal with the Avars and Slavs ended up destabilizing the Byzantine Empire.


Maurice instituted a strict fiscal policy that cut the pay of his soldiers, which between 591 and 602 CE led to four mutinies. In the late winter of 602 CE, he ordered his army into action against the Avars and Slavs, who had invaded the Balkans. An already difficult campaign was made worse by Maurice’s insistence that the army lives off the land and forages for itself. The army revolted and proclaimed the centurion Phocas (547-610 CE) emperor. Phocas besieged Constantinople forcing Maurice to flee. Maurice was captured and executed, along with his entire family. Phocas’ actions were not popular with the population as a whole, and the Byzantine governor of Edessa soon revolted. When Phocas sent an army to retake Edessa, the governor turned to the Sassanians for assistance.


The Early Years 602-608 CE

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Silver Plate Depicting a King Hunting Lions, Sassanian 5th-7th Century CE From The British Museum


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Khosrow II was more than willing to avenge his “friend and father-in-law,” Maurice. Being able to assert his dominance over the Byzantines as well as reconquering Mesopotamia and Armenia were likely just as motivating. In exchange for helping Khosrow II regain his throne, the Persian king had been forced to cede large swathes of territory to the Byzantines. He may have also been forced to acknowledge that the Byzantine emperor was his superior, which would have been an unacceptable humiliation. However, with the murder of Maurice and his family, the situation changed. Khosrow II could portray himself as a loyal avenger of his benefactor, Maurice. His war was a just one and not a betrayal. Additionally, with the murder of Maurice’s family, Khosrow II was able to make a claim to the throne of Constantinople.


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Bowl with a Triumphal Bacchanalian Scene, Sassanian 5th-7th Century CE From The Smithsonian National Museum of Asian Art


The Byzantine-Sassanian war began with the Persians defeating the army that Phocas sent to Edessa and killing its commander. Khosrow II and his great general Shahrbaraz (d.630CE) then pushed into Byzantine territory, quickly regaining much of what had been ceded earlier. The cities of Edessa and Dara were captured in 604 CE. At this point, the former Byzantine governor of Edessa rode to Constantinople in an attempt to salvage the situation through diplomacy. Phocas, however, was unwilling to negotiate and had him burned alive. Having reclaimed the lost Sassanian territory, Khosrow II handed over command of the Byzantine-Sassanian war to Shahrbaraz. Under Shahrbaraz, the Sassanians attacked Syria and Asia Minor, advancing into Chalcedon in 608 CE.


Heraclius’ Revolt 608-610 CE

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Silver Plates Depicting David Being Anointed by Samuel (left) and the Arming of David (right), Byzantine 629-630 CE, From The Metropolitan Museum of Art


Phocas’ inability to deal with the Sassanians and his treatment of the governor of Edessa severely damaged his reputation. He was distrustful of the Byzantine elite, as he was not one of them and had no connections to them. In 608 CE, an appeal was sent to Heraclius the Elder (d.610), who was the Exarch of Africa at that time. Heraclius the Elder proclaimed himself and his son consuls and cut off the vital shipments of grain from Africa. He then sent his nephew Nicetas (d.628/629 CE) to secure Egypt, while the main force under his son, the younger Heraclius, sailed to Constantinople. With the approach of Heraclius’ army, the elite units of the Imperial Guard deserted to his side along with many Byzantine aristocrats.


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Golden Coin Depicting Heraclius and son, Byzantine 610-641 CE, From The British Museum


Heraclius’ army was able to enter Constantinople without much resistance and quickly captured Phocas. After a brief exchange, Heraclius had Phocas executed and proclaimed himself emperor. It was around this time that Heraclius the Elder is believed to have died, as he is no longer mentioned in the records. Phocas’ brother, who was in command of a large army in central Anatolia, was assassinated soon after ending all organized resistance to the new regime. Heraclius set about rebuilding the army and bureaucracy both of which had greatly decayed. Though he built a reputation as a just ruler, he was not always popular with the Church, as he married his niece and limited the number of state-sponsored Church personnel in Constantinople.


Sassanian Supremacy 609-622 CE

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Scabbard with Sheath Snap (left), Sassanian 224-677 CE; with Silver Trim Sword (right), Sassanian 6th -7th Century CE, From The Louvre Museum


While Heraclius was busy seizing the throne at Constantinople, the Byzantine-Sassanian war raged on. The Sassanians were able to use the distraction to seize a series of vital border cities and fortresses between 608 and 610 CE. After assuming the throne, Heraclius attempted to end the Byzantine-Sassanian war through negotiations. Phocas, who had caused the war, was dead. However, Khosrow II did not care. Some have suggested that he was now hoping to create an empire that would rival the Achaemenids. Heraclius, therefore, attempted to reorganize the commanders of the Byzantine army, many of whom had proven themselves incompetent. Despite taking personal command of the army, Heraclius was defeated at Antioch and the Cilician Gates. In 612 CE, Syria and Southern Anatolia fell to the Sassanians, cutting the Byzantine Empire in half.


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Sword Handle and Chapes, Sassanian 7th Century From The Smithsonian National Museum of Asian Art


Resistance to the Sassanians in Syria was not strong, and by 613 CE, all of the major cities in the region had fallen. This allowed the Sassanians to move against Jerusalem, which fell after a three-week siege in 614 CE. The victorious Sassanians looted the city and carried numerous relics, such as the True Cross, Holy Lance, and Holy Sponge, back to their capital at Ctesiphon. By 615 CE, the Sassanians had captured Chalcedon, and Heraclius was willing to become a Persian vassal. His offer was rejected, and the Sassanians withdrew their forces for the invasion of Egypt, which fell in 618 CE. The Sassanians then pushed into central Anatolia while also launching a naval campaign in the Aegean. After the fall of Rhodes and other islands in 622 CE, Heraclius considered abandoning Constantinople and relocating the Byzantine capital to Carthage.


Byzantine Reorganization and Resurgence 615-625 CE

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Silver Plate Depicting David Slaying a Lion, Byzantine 629-630 CE From The Metropolitan Museum of Art


Heraclius recognized the peril that was facing the empire and took drastic measures to reverse the situation. Beginning in 615 CE, he implemented a series of economic and administrative reforms to raise the funds necessary to continue the war. Churches were stripped of their gold and silver to pay new soldiers who were inspired by a crusader-like ideology preached by the clergy. The Sassanian shift to invade Egypt bought Heraclius time to train his new army. By 622 CE, he was ready to take to the field. The Sassanians were first forced to retreat back into Anatolia, and then Heraclius won a smashing victory over Shahrbaraz. This temporarily forced the Sassanians out of Anatolia, which bought the Byzantines more time and space to maneuver.


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Box or Disc Brooch, Avar 6th-7th Century CE From The British Museum


However, the Byzantines were also facing a grave threat in the Balkans. The nomadic Avars and their Slavic vassals had invaded and were laying waste to the region. City after city was sacked, though Thessalonica, the most important city in the region managed to successfully resist several sieges. The Avar invasion prevented Heraclius from sending more troops against the Sassanians. In order to free up his forces, he attempted to negotiate with the Avar Khagan. The initial attempts were a failure, and the Avars tried to capture Heraclius on his way to the negotiations. Eventually, however, in 623 CE, the Avars were induced to return back across the Danube in exchange for hostages and a vast sum of gold. With his rear now secure, Heraclius led his army into Persia via Armenia and Azerbaijan. Between 624 and 626 CE, Heraclius defeated every army sent against him, retook Byzantine cities, sacked Sassanian cities, and directly threatened the Sassanian homeland.


Climax and Constantinople 626-628 CE

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Spangenhelm, Byzantine 6th-7th Century CE From The Metropolitan Museum of Art


Heraclius’ string of victories forced Khosrow II to take drastic action. With one army assembled to defend the Sassanian homeland, Shahrbaraz marched a second army toward Constantinople. The Sassanians had allied themselves with the Avars and planned to besiege Constantinople. However, the powerful Byzantine navy prevented the Sassanians from crossing the Bosporus straits and linking up with the Avars. Without the siege expertise of the Sassanians, the Avars could make little headway against the walls of Constantinople. A Byzantine sally eventually routed the Avars while the Sassanians could do little but watch. At this point, Shahrbaraz intercepted a messenger from Khosrow II, ordering his death. Abandoning the siege, he marched his army back to Syria and adopted a neutral position. He then defected to Heraclius, bringing his entire army over with him.


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Theodosian Walls of Constantinople, Byzantine 4th Century CE From Wikimedia Commons


Heraclius had not been idle. The Byzantines had formed an alliance with the nomadic Khazars, now more commonly known as the Western Turkic Khaganate of the GokTurks. In 625 CE, the Turks took advantage of the Byzantine-Sassanian War to invade the eastern territories of the Sassanian empire. They carved out a vast area of Bactria and Sogdiana, reaching as far as the Indus River. In 626 CE, some 40,000 Turkic warriors joined the Byzantines in the Caucuses to participate in operations against the Sassanians. With a combined army now numbering perhaps 90,000, Heraclius invaded the Sassanian heartland in 627 CE. The Byzantine-Sassanian War had finally reached its climax.


Aftermath of the Byzantine-Sassanian War

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Battle between Heraclius and Chosroes, by Piero della Francesca, 1452-1466, via Wikimedia Commons


Logistical issues and Sassanian raids led to the GoTurks turning back. Nevertheless, when Heraclius engaged the Sassanians at the battle of Nineveh he was able to decisively defeat them; even killing the Sassanian commander in single combat. This Byzantine victory caused Khosrow II to abandon Ctesiphon, his capital city. While the Byzantines were not able to besiege Ctesiphon, they looted the nearby Sassanian palace of Dastagird extensively. Khosrow II had alienated many of his generals by trying to have Shahrbaraz executed. They now rebelled and executed him after raising his son Kavadh II to the throne. Since his position was tenuous, Kavadh II immediately made peace overtures to Heraclius, which he accepted. Since the Byzantine Empire was nearly exhausted, Heraclius’ terms were generous: the return of all captured territory, the release of all prisoners, a war indemnity, and the return of the sacred relics taken from Jerusalem.


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Chalice with St. George Slaying the Dragon, Byzantine 500-650 CE From The Metropolitan Museum of Art


When Heraclius returned to Constantinople, the city was exuberant. Joyful ceremonies were held throughout the city, and the True Cross was raised inside of the Hagia Sophia. Heraclius was hailed as the greatest general since Julius Caesar and celebrated as one of the greatest generals of all time. For the Sassanians, however, the situation was very different. Kavadh II died within months of having brought the war to an end, plunging the weakened empire into a succession crisis. Various generals and members of the royal family vied for the throne. It was not until 632 CE that some order was restored when Yazdegerd III, a grandson of Khosrow II ascended to the throne. However, both empires remained weakened politically, economically, and militarily. They were in no condition to resist the coming storm from the Arabian peninsula.


The Byzantine-Sassanian War Today

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Torso of a Royal Figure, Sassanian 225-650 CE From The Smithsonian National Museum of Asian Art. Crushed Chalice Depicting Christian Saint, Byzantine 500-650 CE From The Metropolitan Museum of Art


The Byzantine-Sassanian War of 602-628 CE was one of Antiquity’s greatest conflicts. While the result of the war was something of a return to the earlier status quo, both empires were significantly weakened. When the Arab Conquest began just a few short years later, neither the Byzantine nor the Sassanians were in any condition to effectively resist. As a result, the Arabs were able to conquer one of the greatest empires the world has ever seen in the space of just over a century. This meant that for centuries the Arab Conquest effectively overshadowed the Byzantine-Sassanian War. Furthermore, Heraclius, who had so heroically resisted the Sassanians, proved incapable of dealing with the Arabs. When he died in 641 CE, much of the empire had been lost, this time permanently.


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Silver Plate Depicting the Battle Between David and Goliath, Byzantine 629-630 CE From The Metropolitan Museum of Art


This means that the most important legacy of the Byzantine-Sassanian War of 602-628 CE is its influence on religion. The war has often been noted for its proto-crusader rhetoric, and religion did play a very important role. The Sassanians appealed to the various religious minority groups within the Byzantine Empire for support. In this, they were quite successful as the Jews and various Christian sects rallied to their cause, though the degree of their support varied greatly. When the Byzantines regained their lost territory, these groups were treated harshly, the effect of which is still felt today. It also made these groups less willing to resist the Arabs and more receptive to converting to Islam. In this way, the legacy of the oft-forgotten Byzantine-Sassanian War of 602-628 CE continues to shape the world in which we live.

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By Robert C. L. HolmesMA Ancient & Medieval History, BA ArchaeologyRobert Holmes has an MA in Ancient & Medieval History and a BA in Archaeology. He is an independent historian and author, who specializes in the Military History of the Ancient and Medieval World and has published over a dozen articles on related topics. Originally from Massachusetts, he now lives in Florida where he works doing public history leading tours, giving lectures, and educating people about the local history.